常规的蛋形屈服面本构模型的屈服函数可经过-平面负半轴，常用于描述重塑土或弱胶结土体的力学特性，但不能准确反映原状软黏土的结构性及其在外部荷载作用下的强度变形机理。在此基础上，本文采用将蛋形屈服面外扩的方式表征土体内部排列形成一定结构带来的强度增长，建立了控制胶结程度的蛋形屈服面参数，结构性外扩系数与塑性累积应变的关系，以运动硬化法则描述了土体在外部荷载作用下结构性衰减的过程，提出了结构性饱和软黏土的蛋形屈服面弹塑性本构模型，并给出了模型参数的确定方法。通过对比结构性饱和软黏土试验结果与该模型的模拟值，验证了模型的合理性。分析了该模型结构性参数对土体压缩特性和三轴不排水剪切特性的影响。该模型能够有效描述结构性土的压缩，应力发展，应变硬化，应变软化等特性。

The yield function of the conventional egg-shaped yield surface constitutive model can pass through the negative semi-axis of the-plane. It is commonly used to describe the mechanical properties of remolded soil or weakly cemented soil, but it cannot accurately reflect the structure of intact soft clay and its strength and deformation mechanism under the action of external loads. Based on this, the paper adopts the method of expanding the egg-shaped yield surface to represent the strength increase brought about by the internal arrangement of the soil forming a certain structure. Establish the relationship among the egg-shaped yield surface parameterwhich controls the degree of cementation, the structural expansion coefficientand the plastic cumulative strain. Describe the process of structural attenuation of the soil under the action of external loads by means of the kinematic hardening rule. Propose an egg-shaped yield surface elastoplastic constitutive model for structurally saturated soft clay. Give the method for determining the parameters. Compare the test results of the structurally saturated soft clay with the simulated values of this model to verify the rationality. Analyze the influence of structural parameters on the compression characteristics and triaxial undrained shear characteristics of the soil. This model can describe the characteristics of structured soil such as compression, stress development, strain hardening, and strain softening.